Furnace wall construction



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FURNACE WALL CONSTRUCTION Filed Nov. 30, 1950 '7 Sheets-Sheet 7 UnitedStates Patent FURNACE WALL CONSTRUCTION Oscar Nygaard, Saugus, Mass,assignor to Bernitz Furnace Appliance Company, Boston, Mass, acorporation of Massachusetts Application November 30, 1950, Serial No.198,318

13 filaims. (Cl. 110-1) This invention relates to improvements infurnace wall construction and especially to an improved front wallrefractory structure for a furnace of the spreader stoker travelinggrate continuous and discharge type in which there is provided a rotormechanism for feeding fuel, together with one or more feed openings inthe front Wall for receiving and guiding fuel from the rotor mechanisminto the combustion chamber of the furnace.

Installation of stoker equipment of this type introduces problems inconnection with providing a satisfactory refractory structure at theinner side of the front wall of the furnace. The exceedingly hightemperatures generated in the spreader stoker furnace of this typeproduces a very great amount of wear and rapid break-down of refractorymaterials such as conventional fire clay bricks and similar products.Use of more heat resistant and durable refractories of the siliconcarbide type, for example, has not been feasible due, in a largemeasure, to the fact that the fabrication process of silicon carbide isentirely difierent from the process of making fire clay refractoryshapes, and involves very costly moulds which wear out rapidly due tothe very high abrasive nature of silicon carbide. Since the size, shape,and lateral spacing of the feed openings and, hence, the refractorymaterials which are to fit around these openings, vary widely inaccordance with the differing specifications of various spreader stokersmanufactured and sold, the expense of making silicon carbide moulds in arange of sizes is prohibitive. The result has been that less resistantrefractories have been made use of and have been built up on the job tofit the varying dimensional requirements, and these refractories aresubject to frequent break-down and repair. This causes interruption ofoperation materially detracting from the efiiciency of the furnaceoperation.

The present invention deals with the problems indicated and aims todevise a more efiicient and economical refractory construction for useat the inner side of the front wall of a furnace of the continuous ashdischarge traveling grate spreader stoker type. It is a further objectof the invention to provide a composite refractory body wherein theshape and construction of the constituent parts are so designed as tomake possible, from an economic standpoint, the use of more heat andabrasion resistant refractories of the silicon carbide type. Stillanother object of the invention is to devise a novel form of siliconcarbide type refractory unit which, in one standard size, can readily beadapted to fit a wide range of dimensional requirements.

These and other objects and novel features will be more fully understoodand appreciated from the following description of a preferred embodimentof the invention selected for purposes of illustration and shown in theaccompanying drawings, in which Fig. l is a vertical, cross-sectionalview taken through a typical fuel inlet opening of the front Wall of afurnace of the continuous ash discharge traveling grate spreader stokertype, showing certain operating parts of the spread- 2,788,753 PatentedApr. 16, 1957 ice er stoker mechanism, and more particularly indicatingportions of the refractory elements of the invention mounted at theinner furnace side of the furnace front wall plate;

Fig. 2 is a fragmentary front elevation of the furnace wall shown inFig. l viewed from the inner furnace side thereof and illustrating oneof the stoker feed openings, together with hanger members of theinvention located in an operative position with respect to the feedopenings;

Fig. 3 is a plan cross-sectional view taken transversely along the line33 of Fig. 2 through a hanger member shown between the feed openings inFig. 2, and illustrating hanger brackets in one position of adjustmentthereon;

Fig. 4 is another cross-sectional view similar to Fig. 3 showing thehanger brackets in an alternative position of adjustment;

Fig. 5 is an isometric view of a clay refractory block employed with thepier hangers of the invention;

Fig. 6 is a top plan view of another form of refractory block employedwith the sill hangers of the invention;

Fig. 7 is a side elevational view of the refractory block shown in topplan view Fig. 6;

Fig. 8 is a top plan view of another form of a clay refractory blockemployed with the sill hangers of the invention;

Fig. 9 is an elevational view of the refractory block shown in Fig. 8;

Fig. 10 is a top plan view of a clay refractory block similar to theblock shown in Figs. 8 and 9 but located on the opposite side of thesill assembly;

Fig. 11 is a fragmentary inside of the furnace elevational View of thesilicon carbide refractory tile members of the invention installed overthe clay refractory blocks in proper relation to the stoker feedopenings;

Fig. 12 is a top plan view, taken on line 1212 of Fig. 11, with the topcap of plastic material removed, and illustrating upper refractory pierforming tile members of the invention arranged in one desired positionof adjustment with respect to the inner side of the furnace front wallplate;

Fig. 13 is a similar plan view,.to the view shown in Fig. 12, butshowing an intermediate position of adjustment of the pier forming tilemembers in relation to the furnace front wall plate;

Fig. 14 is a view similar to Figs. 12 and 13 further illustrating thepier forming members in a third position of adjustment with relation tothe furnace front wall plate;

Fig. 15 is a vertical, cross-sectional view taken on the line 1515 ofFig. 13;

Fig. 16 is another vertical, cross-sectional view taken on the line16-16 of Fig. 11; r v

Fig. 17 is an isometric view of one of the pier forming itile members ofthe invention;

Fig. 18 is a cross-section taken on the line :18-18 of Fig. 11 furtherillustrating the refractory sill forming tile members located on theinner side of the furnace front wall plate;

Fig. 19 is an isometric view illustrating the under side construction ofthe central sill forming tile members of the invention;

Fig. 20 is another isometric view illustrating the under sideconstruction of one of the end sill forming tile members.

In the structure shown in Fig. l of the drawings there has beenillustrated a spreader stoker front wall of a furnace equipped with amechanism of the conventional type including a hopper 10 for holdingfuel, such as comparatively fine coal. The latter is delivered to afeeding table 12 where it is continuously advanced by a pusher member 14across the feed table and caused to fall downwardly into the path ofmovement of a rotor 16 provided with vanes or blades 18 for propellingthe fuel into 3 the furnace. The stoker platform .19 forms the roof overthe stoker vestibule 21. Located below in spaced relation to the roof 19and, protruding partly within the vestibule 21, is a traveling grate 24of conventional construction indicated diagrammatically. Supported uponthe roof 19 of the vestibule 21 is a transversely of the stokervertically positioned metal plate 26 of substantial thickness whichforms the exterior surface of the furnace front wall and comprises apart of the stoker structure. This front plate is provided withlaterally spaced rectangular openings 28 further identified by inwardlyextending lips 30 and located so as to register with the Stoker fuelfeeding mechanism.

. The above brief description of the typical spreader stoker mechanismas shown in the drawings: of this application has been made merely toclarify its functional relationship to the improved refractory wallstructure presently robe described.

accordance with the invention 1. provide an inner refractory wallsection which is designed to withstand the high. temperatures inherentwith this. type of sicker. This inner, wall section is made up ofspaced-apart piers which project inwardly at either side of the fuelinlet openings 28, together with intervening sills which projectinwardly at points below the fuel inlet openings 28. A source of airsupply for cooling the piers and sills, which are hollowstructuressealed tight against air leaks at either sides, top andbottom, is provided by conduits 22 and 23, which communicate with a mainair supply duct 20,, shown clearly in Fig. l, with duet 23 containingdamper means 17 for con-trolling the air pressure to the piers andsills. In my improved refractory wall section I employ very highly heatconductive and heat and abrasion resistant refractory material of thesilicon carbide type, for example, for all surfaces exposed to the fire,and I have devised novel silicon carbide shapes and cooperating. metalhangers the latter being solidly anchored to the. inner side of thefurnace front wall plate 26. These hangers function to locate thesilicon carbide shapes in spaced relation to said front wall plate 26 toconstitute 'a protective apron of air cooled super-refrao t-orymaterial. I also combine refractory material ofa less heat-resistant.and less heat-conductive nature with the silicon carbide shapes andmetalhanger members in order to obtain a composite construction. havingexceedingly high. heat-resistance and protective characteristics, aswill appear hereinafter.

Considering first the hanger members of the invention utilized tosupport the refractory materials, and referring in particular to Fig. 2,numeral 32 denotes a hanger member preferably constructed of high heatresistant alloy steel, orother suitable material, which is solidlybolted to the inner side of the furnace wall plate 26 by means of bolts34 extending through elongated slots 36. The hanger 32- shown in Fig. 2is intended to be representative of a plurality of such members locatedat the opposide sides of fuel inlet openings 23, and may conveniently bereferred to as" pier hangers. Each of these hanger members comprises aflat body portion which bears against the furnace wall and extendsvertically upward, asshown. Integral with this flat body portion is acentral vertical web 38, and intersecting this web at the bottom thereofis a horizontal flange or supporting shelf 40. Inspaced relation toandabove the shelf 40 is a second larger flange or supporting shelf 42, andstill a third-supporting shelfv 44 is locatedin spaced relation abovethe-shelf 42, as shown in Fig. 2. At its upper end the hanger 32 isalsoprovided with a top fimge 46 which forms. abase and support for thecap 45 of preferablyplastic refractory material Figs. 1 and 11. It willbe observedthat the. bot-tom shelf 40 occurs in-spaced relation'ahovethe chain grate member 24 and in an elevated positionz with respect tothe lowermost edge of the refractories, vas is more clearly shown inFig. ll.

a supporting shelf 44 has been further indicated in Figs. 3 and 4whereurrt will .be observed that at one side of the web portion 38 thereis provided a pair of concentric bracket slots 50 and 52 which occur inspaced relation to one another and which have their arcs of curvaturegenerated from a center taken outside of the shelf 44. Similarly, asecond pair of concentric spaced slots 51 and 53 are provided at theother side of the shelf 44. Adjustably supported on the shelf 44 ateither side of the web 33 are two bracket members 54 and 56 beingsecured by means of bolts, as 58 and 6! which pass through the slotsdescribed and hold the bracket members in a desired position ofadjustment. The bracket members include fan-shaped base portionsintegral with which are vertical sides 62 and 64. These sides extendinwardly in an angular direction with respect to the furnace front wallplate 26 and to one another and support at their upper edge rails 66 and68, as shown in Figs. 2 and 3. It will be observed that by moving thebrackets and their holding bolts along the curved slots it is possibleto readily rotate the brackets about a ventical. axis, with the resultthat the position of the sides 62 and as with their respective rails 66and 68 may be varied to a very considerable extent, both with respect tothe angle at which the sides are directed toward the furnace front wallplate, as well as the actual spacing of the rail members from the hangerweb portion 33. A second set of brackets 47 and 49 may, in a similar mamner, be mounted on the hanger shelf 42.

In conjunction. with the pier hangers secured at the sides of. the fuelinlet opening 28,v I provide a plurality of sill hangers which arelocated along that portion of the furnace wall occurring immediatelybelow the fuel inlet opening 28. These sill hangers have been indicatedin Fig. 2 and are denoted by numerals '70, 72 and 74, each of which issimilar in shape. The hangers are formed with vertical body portionswhich are bolted to the furnace front wall plate as shown in Fig. 2 andwhich have integrally formed therewith respective portions 82, 84 and86. Transversely disposed'onrespective shelf portions 82, 84 and 86, andintegral with them, are vertical sides bearing rails 88, 90 and 92. Therails-are located in a fixed position substantially parallel with thefurnace front wall plate and in spaced relation to it, as may be moreclearly seen in Fig. 18. Vertical webs 94, 96 and 98 divide theirrespective shelf portions 76, 78 and into two separate supportingsurfaces.

Areas of the furnace front wall plate 26 occuriug between the severalsill hangers, as well as the pier hangers and the fuel inlet opening 28may, for some installations, be made more heat-resistant by coveringthese surfaces with a layer or sheet of insulating material ofconventional character, as denoted by numeral 100, Figs. 1 and 3..This-insulating material may be applied during the installation of theyhangers and is not essential in all cases. 7

An important feature in the cons-truction andarrangement of the pier andsill hanger members. above described, in. addition to their primaryfunction of supporting refractory shapes, resides in the fact that therefractory shapes are. of such construction, and are so arranged on thehangers thatthey may be installed, removed and replaced by similarshapesin a highly selective manner, independently of one another, and with aminimum amount of labor and time required.

Considering first the refractory shapes for the pier hangers, attentionis directed to Figs. 5, l5 and 16, where'- in there is shown arefractory pier block 102 which is adapted to be mounted on the bottomshelf 40 of the pier hanger 32. As noted in Fig. 5 the pier block has afiat top'and bottom andis'formed with twofrcnt stir faces 162a and 10212which meet at an angle at a point centrally of the block. In-tersectingthe respective sides 102a.and 102?) are two additionaloblique sides 1820and 102d; A vertical slot 194 extends centrally along the upper portionof the block, as noted in Fig. 5, and intersects a second horizontallyextending slot 106 which passes all the way through the block. By meansof these two slots 104 and 106 it will readily be seen that the block102 may be engaged about the web 38 which passes between the sides ofthe block defined by the slot 104 and simultaneously the shelf portion40 is received in the slot 106, thus allowing the block to be firmlylocated on the supporting shelf portion 40 of the hanger.

The block 102 is preferably composed of a refractory material, such asfire clay, or the like, and when mounted about the base of the hanger 32serves to provide a heat insulating layer around the lower portion ofthe hanger and, in addition, provides a substantial mass of insulationat the bottom or under side of the hanger to shield this member fromheat directed upwardly from the chain grate 24. It is also pointed outthat the block 102 closes the space between the vestibule roof 19 andthe fire face apron blocks 120 and serves to seal off the internal airspace within the pier in the manner shown in Fig. 16.

While the clay material block 102 is arranged and designed to protectagainst overheating the metallic pier hanger, the block 102 is in turnprotected against direct exposure to the fire by a further novelstructure forming a protective apron of a silicon carbide type ofrefractory having a much higher heat resisting value than the block 102.This protective apron or skirt comprises a series of pier tiles arrangedin opposed pairs and with respective pairs being superimposed, one aboveanother, in overlapping relation in the manner illustrated in Figs. 11,12 and 16 to accommodate expansion, wherein numeral 120 refers to tilesof a lowermost pair and numeral 122 refers to tiles of an uppermostpair.

Each tile element of a respective pair is of angular shape which combineto make two fire side surfaces 122:: and 12217 separated only by plasticjoint material 127, and which meet at an obtuse angle with two othersurfaces 122a and 122d, as seen in Figs. 1-1, 12, 13 and 14.

The upper edges of the tile elements 120 and the lower edges of the tileelements 122 are formed with complementary shouldered or flangedportions which allow the edges of the respective tiles to lie inoverlapping relation with respect to one another and with vertical sidesof these portions actually being in contact with one another, while thehorizontally extending parts of the shouldered or flanged portions aredisposed in slightly spaced-apart relation, as shown at 129 in Figs. 15and 16 of the drawings.

The slight amount of clearance resulting from this relative arrangementof the upper and lower tile elements permits these members to remain insealed contact with one another and yet they may expand or contract inthe course of their exposure to intense heat without producing excessivestrains and stresses in the material.

In order to support the tile elements in the desired overlappingposition described, the internal pier surfaces of these members areconstructed in the manner illustrated in Fig. 17, as well as Figs. 15and 16. Attention is directed to Fig. 17 where it will be seen thatthere is provided 2. lug extension 124 formed integrally with the tilebody and extending between the two obliquely posh tioned faces of thetile body.

At its under side the extension 124 is recessed to provide an elongatedslot or groove 128 shaped to fit over the rail member 68, Fig. 15, fromwhich the element 122 is suspended to form a shield against the fire. Itis also pointed out that by means of this arrangement the tile member isonly contacting the supporting rail along narrow lines which serve toretard transfer of heat through the refractory into the bracket andhanger structure. In this connection I may also form the rail memberswith serrations or narrow grooves 130 to provide a passageway alongwhich cooling air may pass.

Figs; 12, 13 and 14 show the high temperature resistant tile elements122 supported and suspended on the companion brackets 54 and 56, at amultiplicity of varying angles with respect to the furnace front wallplate.

It will be observed that the end of the tile elements 122 nearest thehanger web portion 38 can be moved outward from the position shown inFig. 12 to that of the position in Fig. 14, to widen the pier at thefurnace front plate and thus bridge any length of the space between thelips or frame portions 30 within the limits shown in Figs. 12 and 14,While the distance between the obtuse corner of the fire face surfaces122a and 122k remain constant. It will also be observed that the meetingedges of the right and left-hand tile elements 122 are so constructedthat a joint contact will always be had irrespective of the angularposition of the tile elements.

Between the outer ends of the apron tile elements and 122 and thefurnace front wall plate, a filling of high heat resistant plasticrefractory material 123 is applied to complete the fire face surfaces122a and 122d, and to form a seal against air leaks from the pierinterior. In connection therewith it will be observed that the endsurface 121 of the lowermost skirt or apron block 120 is provided with aslot 125 to form an anchorage for the plastic filling material toprevent it from slipping downward into the space between the gratesurface 24 and the lower edge of the refractory front wall.

It will thus be seen that with a single combination of a right-hand andleft-hand angular refractory shape, such as is constituted by eithertiles 120 or 122, it is possible to encompass a relatively wide range ofdimensional variations between the feed openings in the furnace frontwall plate and with respect to the size and angularity of the pier.

Since it is an expensive process to mold the refractory tile elements,particularly when these are of highly abrasive silicon carbidematerials, this adjustability feature is an extremely important oneinasmuch as only one mould will be required for any shape shown, yetbeing able to fit any pier Width and angularity with respect to thefurnace front wall plate. The resultant reduced fabrication cost is amajor factor in permitting the silicon carbide refractory members of theinvention to be successfully employed with a great many types ofspreader stoker installations. The importance of this advantage is, ofcourse, more fully appreciated when it is realized that the service lifeand reliability of refractory materials of the silicon carbide type ismuch greater than the ordinary fire clay type of refractory shapes.Hence, very costly shutdowns and idling of large boiler units areprevented.

A generally similar type of composite refractory structure is providedfor mounting on the sill hangers which occur below the feed openings.Attention is directed to Figs. 6 to 10, inclusive, which illustratesuitable refractory blocks of clay brick material 138, as shown in Fig.6, adapted to be engaged over, and to be supported by, the sill hangers70, 72 and 74. These blocks are formed with fiat top and bottom surfaces139 and 141 respectively. At the forward or inner end, the upper portionof the block is tapered back in conformity with the sill angle. A notch149 is made in the tapered surface to provide an air space afterassembly in the wall. At the center of the block the transverse notch isjoined by a recess 143 to the same depth made in the top surface 139, toprovide access of cooling air to the notched out space 140. Along thetwo opposite side edges 145 of the blocks 138 are formed slots 142 whichare adapted to receive therein shelf portions 76, 78 and 80 of therespective brackets 70, 72 and 74, as has been more clearly shown inFigs. 1 and 18.

Although I do not wish to limit myself to any particular arrangement ofrefractory block construction, a preferred arrangement is one in whichblocks similar to the block 138 are supported between hangers 70 and 72and also between hangers 72 and 74. With this arrangement the samedesirable protective features described with respect to the bottom ofthe pier hanger 38 is achieved in the case of each of the sill hangersand adjacent furnace wall areas.

In the. space occurring between the pier block 128 and the adjacent sillhanger 7i), 1 mount a specially formed refractory block of clay brickmaterial, such as that illustrated in Figs. 8 and 9, and denoted bynumeral 148 in the case of a left-hand block and by the numeral 150 Fig.in the case of a right-hand block, as viewed from-a point within thefurnace. As will be seen from an inspection of Fig. 8, the block 148 isformed with an angularly extending side surface 152 which is designed toextend along a plane substantially parallel to the adjacent oblique face126a of the pier block 120. These two latter members may be fittedfairly closely together and a groove 154 may be provided in theangularly extended surface 152 of the block 148 in order to receivebonding material therein.

At its opposite side the block 148 is formed with a slot or groove 156in which may be received the left side edge of the sill flange 76.Similarly, the block 150 Fig. 10 will be arranged on the right sideflange of the opposite sill bracket 80, as shown in Fig. 11, to fill theintervening space between the bracket 80 and the adjacent pier member.

Overlying the clay refractory sill blocks in much the same manner asdescribed in connection with the pier blocks, is provided a protectivesill apron made up of overlapping sill tile elements of silicon carbiderefractory which are more fully disclosed in Figs. 18, 19 and 20. Thesill' tile elements preferably comprise a central tile element 160 andtwo side tile elements 162 and 164 Fig. 11. The central tile member 160has been shown as viewed from its under side in Fig. 19, while one ofthe side tile elements 164 has been shown as viewed from its under sidein Fig. 20.

Referring first to the central tile 16!), shown in Figs.

I of the invention. The conduits 180 and 19.0 are preferably connectedthrough the furnace front wall plate at several different pointstherealong, and in Fig.2 I have shown one 7 suitable arrangementconsisting of an air passageway 182 18 and 19, it will be seen that thetile member is formed with a fire side inclined sill surface 166 whichextends from the edge of the feed opening inwardly and downwardly todefine a diverging guideway for directing fuel into the furnace.

' As noted in Fig. 19, the tile 160 has its under surface formed with anelongated slot 168 adapted to engage over the rail 96 of the hangermember 78. Preferably the length of the elongated slot 168 may exceedthe length of the rail 90 so that some adjustment in directionstransversely of the hanger may be carried out.

At points immediately below the elongated slot 168 the sill tile may beformed with a recessed surface 167 which permits the tile member to fitsnugly down about the sill block 138, as shown in Fig. 18. At its upperinner section the sill tile may be formed with a recess 170 and atransverse rib 172. The latter member is shaped to permit the sill tileto bear against the layer of insulation 100, as shown in Fig; 18, toform a seal over the recessed air providing a greater clearance and afree air flow between the sill tile and the adjacent portions of thehanger and furnace wall, as is also evident from an inspection of Fig.18.

Similarly, the right-hand and left-hand side sill tiles 164 and 162 areformed with rail-engaging slots and ribs, as is shown in Fig. 20, andthe mounting of these members is the same as that already described withthe further addition, however, that these side sill members haveoverlapping'edges 174 adapted to engage with and overlie correspondingrecessed edges 176 of the central sill tile 160. As was the case withrespect to the pier tile, it will be seen that when assembled Fig. 11the adjacent sill tiles will be spaced apart slightly to form aclearance 161 at their meeting edges and may slide upon one another andexpand and contract without developing internal stresses, and yet asubstantial sealed relationship is obtained with respect to the adjacentsill tile members.

In order further to protect the furnace wall against high locatedbetween the two sill hangers 72 .and 74, and a second air passageway 184located at one side of the pier hanger 32. Air may thus be conductedthrough the openin gs 182 into the space occurring between the furnacewall and the sill blocks, finally passing out through the sill tilemembers through especially provided openings 186 as shown in Fig. 11. iI

Similarly, air is conducted through the passageways 134 into the spacebetween the'pier tile and the furnace front wall plate and from thispoint air is circulated around all the surfaces interior of the pier andthen out from the pier through air passageways 188 formed in the frontsides of the pier tile members, as is clearly shown in Fig. 11.

I have found that by thus combining a composite refractory in both thepier and sill structures employing materials of widely differentcharacteristics andwith air circulating means and air venting meanslocated through the various tile members, a very desirable coolingeifect can be realized which aids materially in the success of the tileelements in withstanding the intense heat to which they are subjected.Moreover, by thus utilizing the combined effect of a compositerefractory arrangement and cooling air circulated internally of thecomposite refractory structure, I have found it is practical to moldboth the sill and the pier apron tile shapes of relatively thincross-sectional size, thus greatly reducing the cost of the material forbuilding the inner refractory wall.

I am also enabled to realize another important advantage stemming fromthe fact that the cooling air as it is circulated about the refractoryelements which is capable of very high heat transfer becomes highlypreheated and at its point of discharge into the combustion furnace iscapable of producing increased combustion efliciency.

Another very important result that has been noted during operation withthe construction described herein, is that the fire face surfaces ofboth sills and piers remain relatively clean and free from accumulationsof fly ash and slag. Hence, the proper distribution of the coal ismaintained over the complete grate surface, and bare spots, that wouldpermit the combustion air to, by-pass the fuel bed and thus lower theefiiciency, are definitely eliminated.

From the foregoing description of my invention it will I be appreciatedthat I have disclosed -a novel refractory wall of unique compositestructural aspects wherein a high degree of durability is realized with.a minimum cost. When it is understood that the maximum front'to reardimension for the piers is only about 10 inches and even less for thesill sections, it will be clear that the employment of silicon carbiderefractories in the fire face tile to make a more durable constructionpresented a very ditlicult problem. Since first quality silicon carbiderefractories have a heat transfer coefiicient of 108 B. t. u.s persquare foot per inch thickness per hour as against 10 B. t. u.s for fireclay brick materials, and inasmuch' as all the refractories employednecessarily must be anchored and fully supported upon metal brackets andalso in view of the proximity of the metal furnace front plate due tothe limited wall thickness, it will be understood how readily theintense heat of the furnace could be transferred to the brackets and thefurnace front plate so that these parts would warp and burn out in'avery short time. This problem has been definitely solved by the designpresented in the drawings of this application.

It will be observed that the siliconcarbide shapes, which when assembledform the fire face of the wall, are supported on, and anchored to, themetal brackets or hangers in such a manner that only point or linecontacts are made, thus efiectively reducing the heat transfer to themetal support to a minimum and eliminating the danger of overheatingthese parts, as well as the furnace front plate.

This factor is also augmented in value by reason of the unique apron orskirt-like design and arrangement of the silicon carbide face tile,which provide a very economical use of an exceedingly costly refractorymaterial without any loss of structural strength and stability. Inaddition thereto, since these apron members are made of comparativelythin cross section, permitting a much more efficient air cooling and alarger internal air space within the pier and sill structures withcorrespondingly larger intrenal surfaces in contact with the coolingair, they also act as a very efiective heat screening means for theother component parts of the piers and sills.

An important feature of this invention is that the sills and piersdisclosed herein are separate structures, having no interdependentsupport or anchorage, and each structure is of a construction whichpermits renewals of any of its component parts without interfering withor disturbing any adjacent structure. The facility provided by thisconstruction for replacing any of the members exposed to the fire shouldbe noted. All such members are independently and detachably supported ona companion metal bracket-thus, repairs or renewals can be made quicklyto any part of the furnace wall at the minimum labor cost and boileroutage. When the sill tile is to be renewed, it is merely necessary tolift the old one off its bracket, and replace it with a new one, eachtile being separately renewable, and the center tile can be renewed bymerely lifting the two side tiles to clear the overlapping flanges ofthe center tile, an operation which requires only a minute or two oftime.

If one of the apron tiles of a pier is to be renewed, the refractorycement cap at the top is quickly broken up, which leaves access to thetile. The upper one at either side can then be lifted off its respectivesupports, and the lower tile in turn lifted off its support and renewedif necessary; but the upper one can be changed without disturbing thelower ones, if desired. Of further outstanding importance is theadjustability feature of the silicon carbide pier tile and itssupporting hangers whereby one standard pier tile shape may be employedwith a relatively wide range of required furnace specifications. Withoutthis feature the utilization of silicon carbide refractories for pierconstruction would be hopeless due to the prohibitive cost for making aseparate mould for each variation in shape and size that will berequired because of the multitude of varying angles around the fuelfeeding openings, the multitude of different sizes of fuel feedingopenings, and their spacings from each other.

While I have shown a preferred embodiment of the invention, it should beunderstood that various changes and modifications may be practiced inkeeping with the scope of the appended claims.

I claim:

I. In a furnace of the spreader stoker continuous ash discharge typeincluding an exterior furnace front wall plate having a fuel inletopening therethrough, the combination with' said front wall plate, ofrefractory piers mounted at either side of the feed opening, hangermeans secured to the inner side of the front wall plate below the feedopening, each of said hanger means having a base provided with shelfportions, refractory sill blocks of comparatively low heat conductivityformed with slotted sections which are detachably engaged over the shelfportions, sill members inclined inwardly and downwardly of the furnacefront wall and comprising refractory tile elements of comparatively highheat conductivity and of angular shape located above the sill blocks,the under side of said tile elements being shaped with elongatedgrooves, and said hanger means presenting elongated rail portionsadapted to engage in the elongated grooves of the tile elements anddetachably support the latter members in protective relationship withrespect to the hangers and sill blocks, said refractory sill tilescooperating with the refractory piers to form a diverging guideway forthe fuel.

2. In a furnace of the spreader stoker continuous ash discharge type,including an outer wall section having a fuel inlet openingtherethrough, refractory sills mounted on the inner side of the frontwall at points below the fuel inlet opening, refractory supporting metalhangers secured to the outer front wall section and extending upwardlyat either side of the fuel inlet opening, said hangers having a baseprovided with shelf portions, refractory pier blocks formed with slottedportions which are detachably engaged over the shelf portion, piermembers comprising refractory tile elements of angular shape, said tileelements being located around the refractory pier blocks and hangers andhaving a grooved interior supporting surface, and bracket means movableon the hangers to rotate some of the tile elements about a vertical axisinto varying positions of angularity with respect to the outer wallsection.

3. In a furnace of the type described herein, the combination with anexterior furnace front wall plate formed with a fuel inlet openingtherethrough, of hangers secured at the inner surface of the front wallplate at points below and at either side of the fuel inlet opening, arefractory wall section supported on the hangers in protectiverelationship to the inner surface of the said furnace front plate, saidrefractory wall section including a plurality of overlapping tilemembers arranged in edge to edge relationship to one another and locatedon those hangers occurring below the fuel inlet opening to form a sillinclined downwardly and inwardly of the furnace front wall plate,overlapping angle tile members supported on hangers at either side ofthe fuel inlet opening to provide piers, said piers presenting obliquelydisposed faces with respect to said front wall plate, said facesconverging inwardly toward each other toward the interior of the furnaceand which cooperate with the sill to guide the fuel toward the interiorof the furnace, and means on the respective hangers to adjust the angletile members of the piers about a vertical axis into varying positionsof angularity with relation to the fuel inlet opening and said frontwall plate.

4. A structure as described in claim 3, in which the refractory tilemembers are located in spaced relationship to the front wall plate, toform an inner refractory wall section for cooperatively enclosing aninterior air space between the refractory wall section and the frontwall plate of the furnace, this air space being closed at the top andbottom thereof by other refractory members, means for circulating airbetween the refractory wall section and the front wall plate, and saidangle tile members being formed with air passageways which open into thefurnace interior for conducting heated air into the combustion chamberof the furnace.

5. A device as described in claim 3, in which the base of the refractorywall section includes refractory blocks forming the bottom of the pierand sill structure, and said blocks supported at the lower ends ofrespective hanger members.

6. A structure as defined in claim 3, in which the hanger means for thepier tile members are formed with companion brackets having railportions secured at the upper sides thereof, and each of said tiles hasinner grooved surfaces cooperating with the said rail portion of thecompanion brackets to hold the tiles in a substantially locked position.

7. A device as described in claim 3, in which the hanger members presentvertically spaced shelf portions and integral vertical web portionsextending therebetween in a centrally located position, a plurality oftire brick members formed with slotted portions adapted to engage aboutthe vertical web portions of the hangers and rest upon the said shelfportions.

8. A device as described in claim 3, in which the hanger members includecompanion brackets having horizontal rails of elongated shape and saidtile members are formed with grooved sections adapted to'engage on therails of the companion brackets to provide a substantially narrow lineof contact, thereby to retard heat transmission.

9. In a furnace of the spreader stoker continuous ash discharge type,including an exterior furnace front wall plate having a fuel inletopening therethrough, the combination with said front wall plate ofrefractory sills mounted on the inner side of the front Wall plate atpoints below the fuel inlet opening therethrough, re-

fractory supporting metal hangers secured to the front wall plate andextending upwardly at either side of the fuel inlet opening, each ofsaid hangers having a base provided with shelf portions, refractory pierblocks formed with slotted portions which are detachably engaged overthe shelf portions, pier members comprising refractory tile elements ofangular shape, said tile elements being located about the refractorypier blocks and hangers and having grooved inner surfaces, each of saidpier hangers further including other shelf portions located above saidbase shelf portions for supporting sets of opposed horizontally spacedbrackets, said other shelf portions having means therein which permitslocking said brackets thereto at a plurality of angular positions inrelation to said front wall plate, each of the sets of brackets beingsupported on a shelf of the hanger in vertically spaced position to oneanother, and each bracket of a respective set, at its upper side, beingconstructed with elongated tile supporting rails adapted to engage inthe grooved inner surface of a tile element and detachably support thetile in protective relationship to the refractory pier blocks and in anangularly disposed position with respect to the fuel inlet opening andsaid front wall plate, and said refractory tile elements cooperatingwith the refractory sill to form a guideway for the fuel inwardly flaredtoward the interior of the furnace.

10. A device as described in claim 9, in which said other shelf portionsare formed with slots, and means for adjustably securing said bracketsin the slotted portions of the shelves.

11. A structure as described in claim 9, in which the pier tile elementsare formed with air passageways communicating with the furnace interior,and means for circulating a current of air between the said front wallplate and said tile elements, thereby to provide a cooling effect uponsaid tile elements.

12. In a furnace enclosure comprising a traveling grate forming thefloor thereof, a wall structure, including an exterior metal plate ofsubstantial thickness, having its lower edge elevated-above said door toform a continuous elongated space therebetween to provide an egress forthe continuous disposal of the furnace refuse, a plurality of fuel inletopenings to the furnace exterior through said wall structure, throughwhich fuel may be fed to the furnace by a spreader stoker, said fuelinlet openings being laterally spaced apart in substantially levelrelationship and elevated above the lower edge of said wall; bracketsrigidly attached to said exterior plate at a level below each said fuelinlet opening and above said lower edge of the wall structure, saidbrackets each comprising a pair of vertically spaced integral shelves,the uppermost shelf having an upwardly extending elongated rail portionspaced some distance inwardly from said plate, a prefabricatedrefractory block, having the characteristics of comparatively high heatconductivity and high heat resistance supported and anchored on saidrail portion, a refractory block of comparatively lesser heatconductivity and heat resistance having a body portion forming a part ofthe lower edge of the wall structure and underlying and totallyenclosing the lowermost shelf of said bracket and shielding it from thefurnace heat, while the refractory block of high heat resistance, whichforms a part of the lower boundary of said fuel inlet opening, overliesand shields from the furnace fire both the said lower heat resistantblock and its supporting bracket. i

13. In a furnace of the spreader stoker continuous ash discharge type,including an exterior furnace front wall plate having a fuel inletopening formed therethrou'g h, refractory sills mounted on the innerside of the front wall plate at points below the fuel inlet opening,refractory supporting metal hangers secured to the front wall plate andextending upwardly at either side of the fuel inlet opening; saidhangers having bases provided with shelf portions, refractory pierblocks of comparatively low heat conductivity formed with slottedportions which are detachably engaged and supported over the shelfportions, pier face members comprising refractory tile elements ofrelatively high heat conductivity, said tile elements being supported inan upright position to form a protective shield about the refractorypier blocks and hangers and having a grooved interior supportingsurface, upwardly extending companion bracket means forming a part ofthe hanger, said companion bracket means being adjustable inhorizontally extending slots and being interposed between some of thetile elements of high heat conductive quality and their respectivehangers, said bracket means being formed with rail-like edges to providefor suspending the tile elements on relatively narrow lines of contactthereby to retard heat transmission from the tile elements to thehanger.

References Cited in the file of this patent V UNITED STATES PATENTS787,432

Brett et al. Apr. 18, 1905 1,084,853 Gallagher Jan. 20, 1914 1,281,902Bone Oct. 15, 1918 1,331,774 Kitchen. Feb. 24, 1920 1,410,729 Balz Mar.28,. 1922 1,489,683 Allen -4.-- Apr. 3, 1924 1,539,275 Saathoff May 26',1925 1,665,555 Liptak .Apr. 10, 1928 1,712,849 Sharp May 14, 19291,719,475 lacobus July 2,v 1929 1,766,175 Hosbein June 24, 159301,957,098 Denny May 1,. 1934 2,065,555 Beers Dec. 29,, 1936 2,100,252Hotfman Nov. 23, 1937 2,192,682 Anderson u Mar. 5, 1940 2,418,042Mosshart -2 Mar. 25, 1947 2,431,422 Rehm Nov. 25, 1.947 2,491,547Bennett et al. Dec. 20, I949 2,501,734 Miller Mar. 28, 1950 2,557,456Nichol June 19, 1951 I FOREIGN PATENTS 448,663 Great Britain June 1-2,1936 we. W

